scholarly journals The Role of Pectobacterium atrosepticum Exopolysaccharides in Plant–Pathogen Interactions

2021 ◽  
Vol 22 (23) ◽  
pp. 12781
Author(s):  
Bakhtiyar Islamov ◽  
Olga Petrova ◽  
Polina Mikshina ◽  
Aidar Kadyirov ◽  
Vladimir Vorob’ev ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Soft Rot ◽  
Plant Interactions ◽  
Pectic Polysaccharides ◽  
Phytopathogenic Bacterium ◽  
Pectobacterium Atrosepticum ◽  
Primary Xylem ◽  
Plant Pathogen Interactions ◽  
Bacterial Emboli

The phytopathogenic bacterium Pectobacterium atrosepticum (Pba), one of the members of the soft rot Pectobacteriaceae, forms biofilm-like structures known as bacterial emboli when colonizing the primary xylem vessels of the host plants. The initial extracellular matrix of the bacterial emboli is composed of the host plant’s pectic polysaccharides, which are gradually substituted by the Pba-produced exopolysaccharides (Pba EPS) as the bacterial emboli “mature”. No information about the properties of Pba EPS and their possible roles in Pba-plant interactions has so far been obtained. We have shown that Pba EPS possess physical properties that can promote the maintenance of the structural integrity of bacterial emboli. These polymers increase the viscosity of liquids and form large supramolecular aggregates. The formation of Pba EPS aggregates is provided (at least partly) by the acetyl groups of the Pba EPS molecules. Besides, Pba EPS scavenge reactive oxygen species (ROS), the accumulation of which is known to be associated with the formation of bacterial emboli. In addition, Pba EPS act as suppressors of the quantitative immunity of plants, repressing PAMP-induced reactions; this property is partly lost in the deacetylated form of Pba EPS. Overall, our study shows that Pba EPS play structural, protective, and immunosuppressive roles during Pba–plant interactions and thus should be considered as virulence factors of these bacteria.

scholarly journals Role of the PhoP-PhoQ System in the Virulence of Erwinia chrysanthemi Strain 3937: Involvement in Sensitivity to Plant Antimicrobial Peptides, Survival at Acid pH, and Regulation of Pectolytic Enzymes

2005 ◽  
Vol 187 (6) ◽  
pp. 2157-2162 ◽  
Author(s):  
Arancha Llama-Palacios ◽  
Emilia López-Solanilla ◽  
Pablo Rodríguez-Palenzuela
Keyword(s):  
Bacterial Resistance ◽  
Acid Stress ◽  
Soft Rot ◽  
Erwinia Chrysanthemi ◽  
In Planta ◽  
Phytopathogenic Bacterium ◽  
Low Magnesium ◽  
Acid Ph ◽  
Key Factor

ABSTRACT Erwinia chrysanthemi is a phytopathogenic bacterium that causes soft-rot diseases in a broad number of crops. The PhoP-PhoQ system is a key factor in pathogenicity of several bacteria and is involved in the bacterial resistance to different factors, including acid stress. Since E. chrysanthemi is confronted by acid pH during pathogenesis, we have studied the role of this system in the virulence of this bacterium. In this work, we have isolated and characterized the phoP and phoQ mutants of E. chrysanthemi strain 3937. It was found that: (i) they were not altered in their growth at acid pH; (ii) the phoQ mutant showed diminished ability to survive at acid pH; (iii) susceptibility to the antimicrobial peptide thionin was increased; (iv) the virulence of the phoQ mutant was diminished at low and high magnesium concentrations, whereas the virulence of the phoP was diminished only at low magnesium concentrations; (v) in planta Pel activity of both mutant strains was drastically reduced; and (vi) both mutants lagged behind the wild type in their capacity to change the apoplastic pH. These results suggest that the PhoP-PhoQ system plays a role in the virulence of this bacterium in plant tissues, although it does not contribute to bacterial growth at acid pH.

Role of pectic polysaccharides in structural integrity of apple cell wall material

2008 ◽  
Vol 227 (4) ◽  
pp. 1025-1033 ◽  
Author(s):  
Robert J. Redgwell ◽  
Delphine Curti ◽  
Cécile Gehin-Delval
Keyword(s):  
Cell Wall ◽  
Structural Integrity ◽  
Wall Material ◽  
Cell Wall Material ◽  
Pectic Polysaccharides

scholarly journals Lipid Transporters Beam Signals from Cell Membranes

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 562
Author(s):  
Miliça Ristovski ◽  
Danny Farhat ◽  
Shelly Ellaine M. Bancud ◽  
Jyh-Yeuan Lee
Keyword(s):  
Membrane Proteins ◽  
Lipid Bilayers ◽  
Lipid Composition ◽  
Structural Integrity ◽  
Current Knowledge ◽  
Integral Membrane Proteins ◽  
Cellular Membranes ◽  
Cytoplasmic Proteins ◽  
Lipid Transporters

Lipid composition in cellular membranes plays an important role in maintaining the structural integrity of cells and in regulating cellular signaling that controls functions of both membrane-anchored and cytoplasmic proteins. ATP-dependent ABC and P4-ATPase lipid transporters, two integral membrane proteins, are known to contribute to lipid translocation across the lipid bilayers on the cellular membranes. In this review, we will highlight current knowledge about the role of cholesterol and phospholipids of cellular membranes in regulating cell signaling and how lipid transporters participate this process.

Nitric oxide signalling in plant interactions with pathogenic fungi and oomycetes

2020 ◽  
Author(s):  
Tereza Jedelská ◽  
Lenka Luhová ◽  
Marek Petřivalský
Keyword(s):  
Nitric Oxide ◽  
Current Knowledge ◽  
Biotic Interactions ◽  
Decisive Role ◽  
Pathogenic Fungi ◽  
Plant Colonization ◽  
No Production ◽  
Plant Interactions ◽  
Oriented Growth ◽  
Plant Pathogen Interactions

Abstract Nitric oxide (NO) and reactive nitrogen species have emerged as crucial signalling and regulatory molecules across all organisms. In plants, fungi and fungi-like oomycetes, NO is involved in the regulation of multiple processes during their growth, development, reproduction, responses to the external environment and biotic interactions. It has become evident that NO is produced and used as signalling and defence cues by both partners in multiple forms of plant interactions with their microbial counterparts, ranging from symbiotic to pathogenic modes. This review summarizes current knowledge on NO role in plant-pathogen interactions, focused on biotrophic, necrotrophic and hemibiotrophic fungi and oomycetes. Actual advances and gaps in the identification of NO sources and fate in plant and pathogen cells are discussed. We review the decisive role of time- and site-specific NO production in germination, oriented growth and active penetration of filamentous pathogens to the host tissues, as well in pathogen recognition, and defence activation in plants. Distinct functions of NO are highlighted on diverse interactions of host plants with fungal and oomycete pathogens of different lifestyles, where NO in interplay with reactive oxygen species govern successful plant colonization, cell death and resistance establishment.

The effect of oestrogen withdrawal on cardiac Ca2+ regulation and the influence of GPER1

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
A.J Francis ◽  
J.M Firth ◽  
N Islam ◽  
J Gorelik ◽  
K.T MacLeod
Keyword(s):  
Heart Failure ◽  
Structural Integrity ◽  
Left Ventricular ◽  
Funding Source ◽  
Hormonal Changes ◽  
Ion Conductance ◽  
Developing Heart ◽  
Rapid Stimulation ◽  
Post Menopausal

Abstract Background Post-menopausal women have an enhanced risk of developing heart failure, attributed to declining oestrogen levels during menopause. However, the signalling mechanisms remain undetermined. Purpose We aim to determine the role of G-protein coupled oestrogenic receptor 1 (GPER1) in intracellular Ca2+ regulation and the consequences of hormonal changes that may exacerbate the pathophysiology of heart failure. Methods Ovariectomy (OVx) (mimics menopausal hormone changes) or sham surgeries were conducted on female guinea pigs. Left ventricular cardiomyocytes were isolated 150-days post-operatively for experimental use. Cellular t-tubule network and structural integrity was measured using fluorescent di-8-ANEPPs staining and scanning ion conductance microscopy. GPER1 expression and localisation was measured by Western blot and immunostaining. The role of GPER1 activation was measured using selective agonist G-1 in electrophysiological and Ca2+-sensitive dye fluorescence experiments. Results Following oestrogen withdrawal, the t-tubule network density decreased by 13% and z-groove index reduced by 15%. GPER1 predominantly localised to the peri-nuclear endoplasmic reticulum and its expression increased by 32% in OVx. Action potential duration (APD) prolonged in OVx and following GPER1 activation, APD90 shortened by 11% and 25% in sham and OVx respectively. OVx cells had larger peak inward Ca2+ current (ICaL) (by 22%) and sarcoplasmic reticulum (SR) Ca2+ content (by 13%), compared with sham. While GPER1 activation had little effect on peak ICaL or SR content, it reduced Ca2+ transient amplitude (by 20%), SR fractional release (by 11%) in OVx cells. The frequency of occurrence of spontaneous Ca2+ waves evoked by periods of rapid stimulation reduced by 40% and wave-free survival time prolonged in OVx cells following GPER1 activation. Conclusions In the hearts of an animal species whose electrophysiology and intracellular Ca2+ regulation is akin to humans, we show that following oestrogen deficiency, the t-tubule network is down-regulated and becomes disorganised, GPER1 expression is increased and its activation induces negative inotropic responses in cardiomyocytes. This may limit the adverse changes to Ca2+ signalling reported in OVx that could be pro-arrhythmic and exacerbate the progression to heart failure. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): British Heart Foundation

scholarly journals Role of the Ndc1 interaction network in yeast nuclear pore complex assembly and maintenance

2009 ◽  
Vol 185 (3) ◽  
pp. 475-491 ◽  
Author(s):  
Evgeny Onischenko ◽  
Leslie H. Stanton ◽  
Alexis S. Madrid ◽  
Thomas Kieselbach ◽  
Karsten Weis
Keyword(s):  
Nuclear Pore Complex ◽  
Structural Integrity ◽  
Fluorescent Protein ◽  
Interaction Network ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Binding Partners ◽  
Interaction Partners ◽  
Redundant Functions

The nuclear pore complex (NPC) mediates all nucleocytoplasmic transport, yet its structure and biogenesis remain poorly understood. In this study, we have functionally characterized interaction partners of the yeast transmembrane nucleoporin Ndc1. Ndc1 forms a distinct complex with the transmembrane proteins Pom152 and Pom34 and two alternative complexes with the soluble nucleoporins Nup53 and Nup59, which in turn bind to Nup170 and Nup157. The transmembrane and soluble Ndc1-binding partners have redundant functions at the NPC, and disruption of both groups of interactions causes defects in Ndc1 targeting and in NPC structure accompanied by significant pore dilation. Using photoconvertible fluorescent protein fusions, we further show that the depletion of Pom34 in cells that lack NUP53 and NUP59 blocks new NPC assembly and leads to the reversible accumulation of newly made nucleoporins in cytoplasmic foci. Therefore, Ndc1 together with its interaction partners are collectively essential for the biosynthesis and structural integrity of yeast NPCs.

Neural induction and the structure of the target cell surface

Development ◽  
1982 ◽  
Vol 70 (1) ◽  
pp. 171-187
Author(s):  
A. M. Duprat ◽  
L. Gualandris ◽  
P. Rouge
Keyword(s):  
Cell Surface ◽  
Structural Integrity ◽  
Neural Induction ◽  
Active Role ◽  
Target Cells ◽  
Similar Treatment ◽  
Structural Modifications ◽  
Pleurodeles Waltl

Lectins (SBA and PSA) were used to provoke crowding and structural modifications of the presumptive ectoderm cell surface in order to investigate the role of the membrane organization of the competent target cells in neural induction. Are specific characteristics of the cell surface essential for this phenomenon to occur? From amphibian gastrulae, it is possible to obtain neural induction in vitro by association of presumptive ectoderm (target cells) with chordamesoderm (inductor tissue): 4 h of contact is sufficient in Pleurodeles waltl for transmission of the inductive signal. Very quickly, the treatment of the normal ectoderm by lectins (SBA-FITC or PSA-FITC) provoked surface modifications. Lectin-treatment (50 µg ml1−, 30 min) of presumptive ectoderm did not result in any neural induction. Lectin-treatment (50 µg ml1−, 30 min) of presumptive ectoderm previous to its association with the natural inductor for 4 h, disturbed the phenomenon: no induction. Similar treatment followed by association with the inductor for 24 h: induction. Treatment of SBA or PSA with their respective hapten inhibitors prior to addition to ectodermal cells completely blocked the suppressive effects on induction. The structural integrity of the membrane of competent target cells is necessary for neural induction to occur. The cell membrane could thus play, directly or indirectly, an active role in the specificity of this process

scholarly journals Co-occurrence of latent Dickeya and Pectobacterium species in potato seed tuber samples from northern Finland

2021 ◽  
Vol 30 (1) ◽  
Author(s):  
Yeshitila Degefu
Keyword(s):  
Seed Tuber ◽  
Single Species ◽  
Soft Rot ◽  
Potato Seed ◽  
Pcr Assay ◽  
Diagnostic Pcr ◽  
Pectobacterium Atrosepticum ◽  
Dickeya Solani ◽  
Different Strains ◽  
Potato Seed Tuber

Recent methodological developments have uncovered the etiological diversity of the potato blackleg and soft rot Pectobacteriaceae. At least five species in the genera Dickeya and Pectobacterium have been confirmed to cause blackleg on potatoes in Finland. The bacteria are seed borne and remain latent in the tuber until conditions favourable for growth, multiplication and infection prevail. Tubers could be infected by one or more of these species. This short communication is based on the results of molecular detection data collected for more than 14 years from potato seed lots produced in Finland. Diagnostic PCR assay specific to Dickeya solani, Pectobacterium atrosepticum, Pectobacterium carotovorum, P. brasiliense and P. parmentieri revealed that potatoes are infected by one or more of these species; it also revealed that single species infection is more common than multiple colonization. An event of simultaneous occurrences of different strains from the Pectobacterium species appears to be more frequent than that observed between Dickeya and Pectobacterium species. The absence of co-occurrence of Dickeya solani and Pectobacterium atrosepticum is intriguing.

scholarly journals A review of fungal influenced corrosion of metals

2021 ◽  
Vol 62 (4) ◽  
pp. 333-339
Author(s):  
Imo Okorie ◽  
Romanus Nwokorie
Keyword(s):  
Growth Pattern ◽  
Metal Surfaces ◽  
Structural Integrity ◽  
Great Influence ◽  
Fungal Growth ◽  
Corrosive Media ◽  
Electrochemical Processes ◽  
Single Mechanism ◽  
Growth Of Fungi

The growth of fungi on the surface of metals has great influence on their structural integrity and failure. Their growth on metal surfaces is determined by their secreted metabolites which enable them to adapt to new environmental and nourishment conditions. Although information on the capacity of fungi to adapt to metal surfaces is scarce, most fungi growing on metal surfaces alter the composition of the metals involving it in the process of functional growth and metabolism. Changes in the composition and colour of the metals are some of the evidences confirming that fungus has penetrated the metal surfaces and use it to satisfy its nutritional need with resultant corrosion. In this work we tried to explain different mechanisms of fungal influenced corrosion from different perspectives ranging from the role of biofilms, corrosive media generation by fungal metabolism processes to electrochemical processes generated by fungal growth on metal surfaces. Finally, no single mechanism can conclusively explain all forms of fungal influenced corrosion because every mechanism is unique and applies to individual fungus, its metabolic biproducts or the growth pattern.

scholarly journals Crystal structure of the family 7 endoglucanase I (Cel7B) from Humicola insolens at 2.2 Å resolution and identification of the catalytic nucleophile by trapping of the covalent glycosyl-enzyme intermediate

1998 ◽  
Vol 335 (2) ◽  
pp. 409-416 ◽  
Author(s):  
Lloyd F. MACKENZIE ◽  
Gerlind SULZENBACHER ◽  
Christina DIVNE ◽  
T. Alwyn JONES ◽  
Helle F. WÖLDIKE ◽  
...  
Keyword(s):  
Plant Cell Wall ◽  
Critical Role ◽  
Soft Rot ◽  
Site Directed Mutagenesis ◽  
Cellobiohydrolase I ◽  
Native Form ◽  
Humicola Insolens ◽  
Endoglucanase I ◽  
Enzyme Intermediate

Cellulose is the major polysaccharide component of the plant cell wall and the most abundant naturally produced macromolecule on Earth. The enzymic degradation of cellulose, by cellulases, is therefore of great environmental and commercial significance. Cellulases are found in 12 of the glycoside hydrolase families classified according to their amino acid sequence similarities. Endoglucanase I (Cel7B), from the soft-rot fungus Humicola insolens, is a family 7 enzyme. The structure of the native form of Cel7B from H. insolens at 2.2 Å resolution has been solved by molecular replacement using the known Trichoderma reesei cellobiohydrolase I [Divne, Ståhlberg, Reinikainen, Ruohonen, Pettersson, Knowles, Teeri and Jones (1994) Science265, 524–528] structure as the search model. Cel7B catalyses hydrolysis of the β-1,4 glycosidic linkages in cellulose with net retention of anomeric configuration. The catalytic nucleophile at the active site of Cel7B has been identified as Glu-197 by trapping of a 2-deoxy-2-fluorocellotriosyl enzyme intermediate and identification of the labelled peptide in peptic digests by tandem MS. Site-directed mutagenesis of both Glu-197 and the prospective catalytic acid, Glu-202, results in inactive enzyme, confirming the critical role of these groups for catalysis.

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